192 ROYAL SOCIETY OF CANADA 



current eastward during the ebb, even tliough assisted by the under- 

 current. The gale itself is rather to be taken as an indication of a 

 marked difference of barometric pressure, which had a general influence 

 on the direction of the dominant flow at the time. 



Conclusions regarding wind disturbance in Belle Isle strait. — The 

 effect of the wind in Belle Isle strait in raising a sea quickly, is very 

 noteworthy; but any direct effect upon the movement of the water, as 

 far as careful observation can detect, is remarkably slight. 



Most of the effects usually ascribed to the wind have been found on 

 investigation to be due to other causes. Yet it is true that the wind itself 

 may afford an indication of the existence and operation of such causes 

 as those which may influence the direction of the dominant flow. But 

 the strong preponderance of flow in one direction during quiet weather, 

 and the small difference in time between the turn on the surface and in. 

 the under-current, show clearly that this dominant flow is not of the 

 nature of a wind drift. 



The actual influence of the wind upon the movement of the water, 

 may be summarized as follows: — ■ 



(1) It is anything but true that the current always sets with the 

 wind which is blowing locally in the strait; since the ordinary tidal 

 streams as they turn, will set directly against the wind, even when it is 

 fairly heavy. On the other hand, in unsettled weather, the wind often 

 comes up with the turn of the tide; or it is held back until slack water 

 by the tidal stream setting against it. 



(2) There was no evidence, after any of the gales, that the wind 

 was able to reverse the direction of the tidal streams, or that it was able 

 to check to any noticeable extent, the dominant flow which prevailed at 

 the time. 



(3) From direct comparisons of the velocities of the surface and 

 under-current, made in 1894, it appears that when a period of several 

 days is considered as a whole, the current which sets against the wind 

 prevailing at the time, is somewhat retarded on the surface. This is 

 inferred from the velocity it otherwise would liave had, as indicated by 

 the imder-current. 



(4) The only other effects of the Avind upon the movement of the 

 water wliich can be detected, are these : — There may be a slight change 

 in the time of veering at the turn of the current when it is weak; and 

 the period of flood or ebb which is in the direction of the wind may be- 

 come sliglitly longer on the surface than in the under-current. 



These results are based upon observations taken as soon as the wea- 

 ther moderated. If the effects are greater while a gale lasts, the current 

 must recover its usual behaviour almost at once, when the wind falls. 



